The present invention relates to a developing device for an image forming apparatus, a process cartridge and an electric energy supply part therefor.
Here, the image forming apparatus forms an image on a recording material through an electrophotographic process for example. Examples of the electrophotographic apparatus include an electrophotographic copying machine, electrophotographic printer (for example a laser beam printer, LEDprinter or the like), facsimile machine, word processor and the like.
The process cartridge contains an image bearing member and at least one charging means, developing means and cleaning means, which are unified into a cartridge which is detachably mountable to an image forming apparatus.
In the field of an electrophotographic image forming apparatus using an electrophotographic image forming process, a process cartridge type is used in which an electrophotographic photosensitive drum and process means actable on the electrophotographic photosensitive drum are unified into cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. With this process cartridge type, the maintenance operation for the electrophotographic image forming apparatus can be carried out in effect by the users, so that operativity is remarkably improved. Therefore, the process cartridge type is widely used in the field of image forming apparatus.
In the process cartridge, an electrostatic latent image formed on the electrophotographic photosensitive member is developed by developing means which develops the electrostatic latent image formed on the electrophotographic photosensitive member with the toner (developer) by a developing roller which is a developer carrying member. More particularly, a developing bias is applied to the developing roller to transfer the toner onto the electrophotographic photosensitive member from the developing roller in accordance with the electrostatic latent image so that visualized toner image is provided.
As for the method for applying a developing bias the developing roller, as shown in FIG. 10, a flange member F of an electroconductive material is provided at the end of the developing roller D, and an electrode in the form of a compression coil spring Sp is mounted to the flange member F for electrical conduction. When the developing device is mounting to the main assembly of the operators, the contact member C is electrically connected to an electric energy supply member V provided in the main assembly of the apparatus.
As for another method of applying a developing bias the developing roller, as shown in FIG. 11 an elastic contact portion Cs is provided in the contact member C, and the elastic contact portion Cs is contacted to flange member F of electroconductive material at an end of the developing roller D. When the developing device is mounted to the main assembly of the apparatus, the contact member C is electrically connected to the electric energy supply member V provided in the main assembly of the apparatus.
In such a case, the compression coil spring Sp or the flange member F is rotated integrally with the developing roller D so that it is in sliding relation with the contact member C, and therefore, generally, electroconductive grease is applied the sliding portion Cp.
Accordingly, it is a principal object of the present invention to provide a developing device and an assembling method in which a contact portion for applying a developing bias to a developer carrying member is improved in reliability.
It is another object of the present invention to provide a process cartridge and an assembling method in which a contact portion for applying a developing bias to a developer carrying member. It is a further object of the present invention to provide an electric energy supply part in which an electric energy supply part for electric energy supply of developing bias to a developer carrying member has a magnet with which the positional accuracy in the developer carrying member is improved.
It is a yet further object of the present invention to provide an electric energy supply part for electric energy supply of developing bias away developer carrying member with which an electrical connection with an electroconductive portion on a magnet disposed inside said developer carrying member.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.